Re: servo or stepper size selection

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "sparkness2001 <mark@c...>"
<mark@c...> wrote:

> I have an old mill (1965 index)in great shape it is 9 x 40 and its
> lead screws are 1.125 dia. .200 lead i am planning to change the

lead

> screws to ball and cnc of some sort. I have a pc for the job now

im

> looking for best or should i say reasonable way to go, servo or
> stepper ive been on ebay and looked at many sites for home cnc. I
> want to have an accurate and reasonable to program cnc setup
> any help would be appreciated. thanks --mark

I'm building now a CNC machine with servo motors. I've had also the
same question, and also did the same question. There are two aspects
to consider: 1 - the price and 2 - the performance.

Servo motors can have more torque at greatest speeds, while steppers
don't (check the graphics of speed vs torque). Also, steppers are
told to do a step, for example, and without feedback, if it was not
done (for several reasons), then you lost him - servos are used in a
closed loop control, with enconders. But if the steppers are good,
and if enough torque is avaiable for what you are moving then it
seems ok to go for steppers.

Servos are more expensive, but I think that they compensate the price.
If you have questions, then look to some industrial machines and you
will see that the serious ones use servo motors. This was one of the
main influences for me.

I'm still learning - so don't take for sure my info. You can still
ask again to someone else.

If you are living in Europe, I'm looking for a couple of persons to
buy servos from the USA, for less expenses.

Filipe Tomaz